The Nuxeo Groups and Rights Audit package requires no specific installation steps. It can be installed like any other package from the Marketplace or from the Admin Center.
After it has been installed, administrators have a new document action option available, called "Permission Audit Export".
The Nuxeo Groups and Rights Audit addon sends email to the administrator who requested the audit. So your Nuxeo server must be able to reach an e-mail server. This is the same configuration that the one required for the email alerts to work. See how to enable e-mail alerts.
The default timeout to process the export of rights is 1200 seconds (20 minutes). You can change this default timeout by adding the parameter
nuxeo.audit.acl.timeout to the nuxeo.conf file and defining another value than 1200, like 3600 (1 hour) for instance.